Is there a native templating system for plain text files in Python?

Question

I am looking for either technique or templating system for Python for formatting output to simple text. What I require is that it will be able to iterate through multiple lists or dicts. It would be nice if I would be able to define template into separate file (like output.templ) instead of hardcoding it into source code.

As simple example what I want to achieve, we have variables title, subtitle and list

title = 'foo'
subtitle = 'bar'
list = ['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday', 'Sunday']

And running throught a template, output would look like this:

Foo
Bar

Monday
Tuesday
Wednesday
Thursday
Friday
Saturday
Sunday

How to do this? Thank you.

I don't know if it is simple, but [Cheetah](http://www.cheetahtemplate.org/) might be of help. — Jeannot, Jun 17 '11 at 12:41

score 272 · Answer 1 · edited Nov 04 '20 at 00:04

272

You can use the standard library string an its Template class.

Having a file foo.txt:

$title
$subtitle
$list

And the processing of the file (example.py):

from string import Template

d = {
    'title': 'This is the title',
    'subtitle': 'And this is the subtitle',
    'list': '\n'.join(['first', 'second', 'third'])
}

with open('foo.txt', 'r') as f:
    src = Template(f.read())
    result = src.substitute(d)
    print(result)

Then run it:

$ python example.py
This is the title
And this is the subtitle
first
second
third

edited Nov 04 '20 at 00:04

ivanleoncz

9,070
7
57
49

answered Jun 17 '11 at 12:47

ThibThib

8,010
3
30
37

Where, please, does the dictionary go? Is it a separate file (and where is it stored), or is it included within the Python script, or included within foo.txt? – lawlist Apr 07 '13 at 01:38
@lawlist: Added a full example at the end. The only thing missing were declarations for the data to be replaced into the template. – Sergio Acosta Apr 29 '13 at 15:28
Why does the initial code snipped of *foo.txt* have a trailing `$` for the placeholders. That kinda threw me off a bit because it generates errors. – Batandwa Apr 24 '14 at 19:35
5

Use `$$` to escape and output `$`. – Batandwa Apr 24 '14 at 19:38
@Batandwa I don't get an error. Single `$` works fine on Python 3.4 – Omid Oct 21 '15 at 16:31
do you need to close the file? – simplename May 11 '18 at 17:27
@Batandwa I do get an error on Python 2.7.3 and using $$ fixes it. Thanks from four years later. – GDYendell Jul 12 '18 at 16:27

score 19 · Accepted Answer · answered Jun 17 '11 at 12:36

19

There are quite a number of template engines for python: Jinja, Cheetah, Genshi etc. You won't make a mistake with any of them.

answered Jun 17 '11 at 12:36

jammon

3,404
3
20
29

6

did the OP say 'native'? And validated something that isn't! – Noel Nov 05 '21 at 12:44

Oben Sonne · Answer 3 · 2011-06-17T12:58:06.957

19

If your prefer to use something shipped with the standard library, take a look at the format string syntax. By default it is not able to format lists like in your output example, but you can handle this with a custom Formatter which overrides the convert_field method.

Supposed your custom formatter cf uses the conversion code l to format lists, this should produce your given example output:

cf.format("{title}\n{subtitle}\n\n{list!l}", title=title, subtitle=sibtitle, list=list)

Alternatively you could preformat your list using "\n".join(list) and then pass this to your normal template string.

edited Jun 17 '11 at 12:58

answered Jun 17 '11 at 12:40

Oben Sonne

9,893
2
40
61

1

Dead simple for CLI output templating :) – m3nda Oct 09 '15 at 20:20
3

Here is an example how to do this: https://makina-corpus.com/blog/metier/2016/the-worlds-simplest-python-template-engine . A simple template engine with loops and conditions in 10 lines of code. – asmaier Nov 08 '16 at 14:34

user1050755 · Answer 4 · 2023-01-06T11:57:30.593

1

if you want arbitrary prefixes/suffixes to identify your variables, you can simply use re.sub with a lambda expression:

from pathlib import Path
import re

def tpl(fn:Path, v:dict[str,str]) -> str:
    text = fn.with_suffix('.html').read_text()
    return re.sub("(<!-- (.+?) -->)", lambda m: v[m[2].lower()], text)

html = tpl(Path(__file__), {
    'title' : 't',
    'body' : 'b'
})

edited Jan 06 '23 at 11:57

answered Jan 06 '23 at 11:41

user1050755

11,218
4
45
56

Is there a native templating system for plain text files in Python?

4 Answers4

Linked

Related